1. Field of the Invention
The present invention relates to an image pickup apparatus including a solid-state image pickup device such as a charge-coupled device (CCD) image sensor or a complementary metal-oxide semiconductor (CMOS) image sensor, as well as an image data processing apparatus, an image data outputting method, an image data processing system and an image pickup device.
2. Description of the Related Art
Image pickup apparatuses such as digital still cameras or digital video cameras include a solid-state image pickup device such as a CCD image sensor. Such a solid-state image pickup device may have so-called defective pixels formed during production, which are unable to generate a charge according to the amount of received light or which generate noise exceeding a rated value due to unevenness in a dark current.
When the image signal of the defective pixel is displayed, it appears in a picked up image as a defect such as a black noise or a white noise, and significantly degrades the quality of the image. Therefore, when a solid-state image pickup device is produced, whether or not the solid-state image pickup device includes defective pixels is determined during an inspection process. If the solid-state image pickup device includes defective pixels, “defective pixel data”, which represents, for example, the positions (coordinates) of the defective pixels, are stored in advance in a storage section (memory) of an image pickup apparatus.
Image pickup apparatuses include an image defect correction device, which corrects defects caused by the defective pixels on the basis of the above “defective pixel data”. An example of a technology relating to such an image defect correction device is described in Japanese Patent Application Laid-open (JP-A) No. 1-105671.
Namely, the image defect correction device described above corrects only the defective pixels corresponding to the “defective pixel data”,which is stored in advance, on the basis of data of neighboring pixels surrounding each of the defective pixels during the actual picking up of the image. The reason why only the “defective pixel data”, which are stored in advance in the memory, are used for correcting the defective pixels is to expedite the actual image picking up process, such as when shooting serial images or a moving image. The above-described method for correcting defective pixels is needed for a compact, light and inexpensive digital still camera.
Regarding the above-described digital still camera, an upper limit of a storage capacity of a memory for storing the “defective pixel data” is determined in advance by considering factors such as cost. The number of defective pixels storable in a typical memory is limited up to 256-1000. Therefore, in order to obtain a good image, defective pixels within the storage capacity of the memory are appropriately corrected on the basis of data of neighboring pixels surrounding each of the defective pixels.
Further, some conventional digital still cameras include an encrypting means for encrypting image data so that an image of the image data can not be viewed by a third party. An example of a technology relating to such encryption is described in JP-A No. 2000-165720.
Assuming that a sales system for selling a so-called single-use type digital still camera, which is lent to and collected from unspecified users, is established, a third party who has rented such a digital still camera may use (divert use of) its image pickup device such as a CCD image sensor or a CMOS image sensor in another image pickup apparatus. It should be noted that, when the above-described image data is encrypted, the encryption imposes an additional load on processing carried out in the image pickup apparatus. Hence, there is a need for improved image pickup technology.